[syzbot] [tipc?] general protection fault in tipc_named_node_up

[syzbot] [tipc?] general protection fault in tipc_named_node_up

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    20a33c6b6cbe Add linux-next specific files for 20261023
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1000e5e0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b72dfd5e7ab2b781
dashboard link: https://syzkaller.appspot.com/bug?extid=64197f7577a09686ffdb
compiler:       Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15c25b0d580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13c25b0d580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/cfbd1ccc6546/disk-20a33c6b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c36184d6a775/vmlinux-20a33c6b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/48b7e871397c/bzImage-20a33c6b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+64197f7577a09686ffdb@syzkaller.appspotmail.com

tipc: Enabling of bearer <eth:syz_tun> rejected, already enabled
Oops: general protection fault, probably for non-canonical address 0xdffffc000000001b: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x00000000000000d8-0x00000000000000df]
CPU: 1 UID: 0 PID: 6165 Comm: syz.4.85 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
RIP: 0010:buf_msg net/tipc/msg.h:202 [inline]
RIP: 0010:named_distribute net/tipc/name_distr.c:195 [inline]
RIP: 0010:tipc_named_node_up+0x8e0/0xb00 net/tipc/name_distr.c:221
Code: 41 2b f6 48 8d b4 24 80 00 00 00 48 8b 84 24 88 00 00 00 31 db 48 39 f0 48 0f 45 d8 48 81 c3 d8 00 00 00 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 74 10 48 89 df e8 21 12 a2 f6 48 8d b4 24 80 00 00
RSP: 0018:ffffc9000407f2e0 EFLAGS: 00010206
RAX: 000000000000001b RBX: 00000000000000d8 RCX: ffff88802a719f40
RDX: 0000000000000000 RSI: ffffc9000407f360 RDI: 0000000000000001
RBP: ffffc9000407f430 R08: ffff8880352dc007 R09: 1ffff11006a5b800
R10: dffffc0000000000 R11: ffffed1006a5b801 R12: ffff88805d6e4000
R13: dffffc0000000000 R14: 0000000000000456 R15: ffff88805d6e6020
FS:  0000555560621500(0000) GS:ffff888123511000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fffd16d5c70 CR3: 0000000077bdc000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 tipc_node_write_unlock+0x2ce/0x4f0 net/tipc/node.c:428
 tipc_rcv+0xb55/0x1020 net/tipc/node.c:2196
 tipc_l2_rcv_msg+0x2d9/0x470 net/tipc/bearer.c:671
 __netif_receive_skb_one_core net/core/dev.c:6405 [inline]
 __netif_receive_skb net/core/dev.c:6518 [inline]
 netif_receive_skb_internal net/core/dev.c:6604 [inline]
 netif_receive_skb+0x4af/0xbf0 net/core/dev.c:6663
 tun_rx_batched+0x1de/0x790 drivers/net/tun.c:1575
 tun_get_user+0x2b78/0x4470 drivers/net/tun.c:2053
 tun_chr_write_iter+0x113/0x200 drivers/net/tun.c:2100
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x612/0xba0 fs/read_write.c:687
 ksys_write+0x150/0x270 fs/read_write.c:1036
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f737d15fd8e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007fff46919968 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000555560621500 RCX: 00007f737d15fd8e
RDX: 0000000000000046 RSI: 0000200000000140 RDI: 00000000000000c8
RBP: 00007f737d236b20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f737d425fac R14: 00007f737d425fa0 R15: 00007f737d425fa0
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:buf_msg net/tipc/msg.h:202 [inline]
RIP: 0010:named_distribute net/tipc/name_distr.c:195 [inline]
RIP: 0010:tipc_named_node_up+0x8e0/0xb00 net/tipc/name_distr.c:221
Code: 41 2b f6 48 8d b4 24 80 00 00 00 48 8b 84 24 88 00 00 00 31 db 48 39 f0 48 0f 45 d8 48 81 c3 d8 00 00 00 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 74 10 48 89 df e8 21 12 a2 f6 48 8d b4 24 80 00 00
RSP: 0018:ffffc9000407f2e0 EFLAGS: 00010206
RAX: 000000000000001b RBX: 00000000000000d8 RCX: ffff88802a719f40
RDX: 0000000000000000 RSI: ffffc9000407f360 RDI: 0000000000000001
RBP: ffffc9000407f430 R08: ffff8880352dc007 R09: 1ffff11006a5b800
R10: dffffc0000000000 R11: ffffed1006a5b801 R12: ffff88805d6e4000
R13: dffffc0000000000 R14: 0000000000000456 R15: ffff88805d6e6020
FS:  0000555560621500(0000) GS:ffff888123511000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fffd16d5c70 CR3: 0000000077bdc000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	41 2b f6             	sub    %r14d,%esi
   3:	48 8d b4 24 80 00 00 	lea    0x80(%rsp),%rsi
   a:	00
   b:	48 8b 84 24 88 00 00 	mov    0x88(%rsp),%rax
  12:	00
  13:	31 db                	xor    %ebx,%ebx
  15:	48 39 f0             	cmp    %rsi,%rax
  18:	48 0f 45 d8          	cmovne %rax,%rbx
  1c:	48 81 c3 d8 00 00 00 	add    $0xd8,%rbx
  23:	48 89 d8             	mov    %rbx,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 28 00       	cmpb   $0x0,(%rax,%r13,1) <-- trapping instruction
  2f:	74 10                	je     0x41
  31:	48 89 df             	mov    %rbx,%rdi
  34:	e8 21 12 a2 f6       	call   0xf6a2125a
  39:	48                   	rex.W
  3a:	8d                   	.byte 0x8d
  3b:	b4 24                	mov    $0x24,%ah
  3d:	80 00 00             	addb   $0x0,(%rax)


---
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Forwarded: #syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git d135ab453a7400a34930bdda1ef4bdc8acfac80e

[syzbot]

For archival purposes, forwarding an incoming command email to
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***

Subject: #syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git d135ab453a7400a34930bdda1ef4bdc8acfac80e
Author: dmantipov@yandex.ru

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git d135ab453a7400a34930bdda1ef4bdc8acfac80e

Forwarded: #syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git d135ab453a7400a34930bdda1ef4bdc8acfac80e

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: #syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git d135ab453a7400a34930bdda1ef4bdc8acfac80e
Author: dmantipov@yandex.ru

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git d135ab453a7400a34930bdda1ef4bdc8acfac80e